The present invention relates to polymeric ligands, polymeric metallocenes, catalyst systems, processes for preparing same, and olefin polymerization processes.
Metallocene catalysts have been used in homogeneous solution polymerizations. Attempts to use soluble metallocene catalysts in a slurry or particle form type polymerization are currently not commercially feasible. It has been observed that when such particle form polymerizations are carried out in the presence of a soluble metallocene catalyst, large amounts of polymeric material are formed on the surfaces of the polymerization vessel. This fouling produces an adverse effect on the heat transfer and also results in the need for periodic, if not continuous, cleaning of the reactor.
It would therefore be desirable to produce economical metallocene catalysts useful in polymerization processes free of reactor fouling.
For many applications, such as thermoforming, extrusion, blow molding and the production of film, it is desirable to produce a polymer having a broad molecular weight distribution.
It would therefore be desirable to produce metallocene catalysts capable of producing polymers having a broad molecular weight distribution.
Another important characteristic of polymers is the environmental stress crack resistance, which can be improved by the incorporation of comonomer in the high molecular weight portion of polymers having a broad molecular weight distribution.
An object of the present invention is to provide a polymeric ligand useful in preparing polymeric metallocenes.
Another object of the present invention is to provide an economical process for preparing a polymeric ligand.
Another object of the present invention is to provide a polymeric metallocene useful in olefin polymerization which does not produce significant reactor fouling in a particle form polymerization process.
Another object of the present invention is to provide mixtures of polymeric metallocenes useful in preparing polymers having a broad molecular weight distribution.
Another object of the present invention is to provide mixtures of polymeric metallocenes useful in preparing polymers having improved environmental stress crack resistance.
Another object of the present invention is to provide an efficient and economical process for preparing polymeric metallocene catalysts.
Still another object of the present invention is to provide a polymerization process free of significant reactor fouling, especially in particle form processes.
In accordance with the present invention, polymeric ligands, polymeric metallocenes, catalyst systems, processes for preparing same, and polymerization processes are provided. The process for preparing polymeric metallocenes comprises reacting a polymeric ligand, an alkali metal compound, and a transition metal-containing compound, wherein the polymeric ligand contains a cyclopentadienyl-type group, as hereinafter defined, wherein the transition metal-containing compound is represented by the formula MX4 wherein M is a transition metal, and each X is individually a hydrocarbyl group containing 1 to 20 carbon atoms, an alkoxy group containing 1 to 12 carbon atoms, an aryloxy group containing 6 to 20 carbon atoms, a halide, or hydride. In another embodiment, a process for preparing polymeric ligands comprises reacting at least one bridged cyclopentadienyl-type monomer, as hereinafter defined, and an initiator under polymerization conditions. In another embodiment, polymeric ligands are represented by the formula [Qxe2x80x2]n, wherein Qxe2x80x2 is a unit containing at least one bridged cyclopentadienyl-type group and wherein n is 1-5000. Polymeric ligands comprising mixtures of bridged and unbridged cyclopentadienyl-type groups are also provided. In another embodiment, polymeric metallocenes are represented by the formula [Qxe2x80x3MXm]n, wherein Qxe2x80x3 is a unit containing at least one fluorenyl-type group, as hereinafter defined, M is a transition metal, each X is individually a hydrocarbyl group containing 1 to 20 carbon atoms, an alkoxy group containing 1 to 12 carbon atoms, an aryloxy group containing 6 to 20 carbon atoms, a halide, or hydride, m is 2 or 3, and wherein n is 1-5000. The catalyst systems comprise the polymeric metallocene and an organoaluminoxane. The polymerization process comprises contacting the catalyst system and at least one olefin under polymerization conditions.
A process for preparing polymeric metallocenes comprises reacting a polymeric ligand, an alkali metal compound, and a transition metal-containing compound.
The polymeric ligand employed in preparing the polymeric metallocene is represented by the formula [Q]n, wherein Q is a unit containing at least one cyclopentadienyl-type group and wherein n is 1-5000, preferably 3-1000. Cyclopentadienyl-type, as used herein, includes groups containing a cyclopentadienyl functionality, and includes cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl and substituted fluorenyl groups. Fluorenyl-type groups are preferred. Fluorenyl-type as used herein includes groups containing a fluorenyl functionality, and includes fluorenyl and substituted fluorenyl containing compounds. Typical substituents for the above defined cyclopentadienyl-type groups include hydrocarbyl groups containing 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, alkoxy groups containing 1 to 12 carbon atoms, or halide. Preferably the substituents are alkyl groups containing 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. Some examples of substituents include methyl, ethyl, propyl, butyl, tert-butyl, isobutyl, amyl, isoamyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, dodecyl, 2-ethylhexyl, pentenyl, butenyl, phenyl, chloride, bromide, and iodide.
Examples of typical cyclopentadienyl-type groups include fluorene, vinylcyclopentadiene, (1-methylethenyl)cyclopentadiene, (1-(4-vinyl)phenyl)cyclopentadiene, penta-2,4-dienylcyclopentadiene, 2-vinyl-7-methylfluorene, 1-vinyl-3-butylcyclopentadiene, 2,7-dimethyl-9-vinylfluorene, 1-vinylindene, 2-vinylindene, 3-vinylindene, 4-vinylindene, 5-vinylindene, 6-vinylindene, 7-vinylindene, 1-vinylfluorene, 2-vinylfluorene, 3-vinylfluorene, 4-vinylfluorene, 5-vinylfluorene, 6-vinylfluorene, 7-vinylfluorene, 8-vinylfluorene, 9-vinylfluorene, and mixtures thereof.
The term polymeric, as used herein, is intended to include both homopolymers and copolymers. Copolymers can include mixtures of cyclopentadienyl-type groups and/or other polymerizable monomers. The term polymerization, as used herein, is intended to include both homopolymerization and copolymerization. The term monomer, as used herein, refers to a compound capable of undergoing polymerization.
In addition to the at least one cyclopentadienyl-type group, the unit Q can also contain other groups, such as styrene. When styrene is employed, the relative amount of styrene and cyclopentadienyl-type group can vary broadly depending on the particular results desired. Generally, when employing a styrene comonomer, the styrene will be present in an amount in the range of from about 0.1 mole to about 5000 moles styrene per mole of cyclopentadienyl-type group, preferably styrene is present in the range of from about 0.1 mole to about 1500 moles styrene per mole cyclopentadienyl-type group, and more preferably from 1 mole to 1000 moles styrene per mole cyclopentadienyl-type group.
The polymeric ligands can be prepared by any method known in the art. Examples of some such methods are disclosed in U.S. Pat. No. 3,079,428, Journal of Polymer Science: Polymer Chemistry Edition, Vol. 23, 1433-1444 (1985), and Journal of Polymer Science, Polymer letters, Vol. 9, 671-676 (1971), the disclosures of which are incorporated herein by reference.
One method for preparing the polymeric ligand involves radical polymerization by reacting an initiator and at least one cyclopentadienyl-type monomer under polymerization conditions. Suitable initiators include azobisisobutyronitrile, phenyl-azo-triphenylmethane, tert-butyl peroxide, cumyl peroxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, tert-butyl hydroperoxide, and tert-butyl perbenzoate. The method is also effective when employing styrene as comonomer. Generally the reaction is conducted in the presence of a diluent such as toluene. Generally conditions suitable for the radical polymerization of the cyclopentadienyl-type monomer will include a temperature in the range of from about 0xc2x0 C. to about 150xc2x0 C.
Another method for preparing the polymeric ligands involves cationic polymerization by reacting an initiator, such as boron trifluoride etherate, and a cyclopentadienyl-type monomer under polymerization conditions. Generally the reaction is conducted in a diluent such as methylene chloride. The method is also effective when employing styrene as comonomer. Suitable cationic polymerization conditions for preparing the polymeric ligand include a temperature in the range of from about xe2x88x9280xc2x0 C. to about 0xc2x0 C.
Still another method for preparing the polymeric ligands involves alkylating polymerization by reacting zinc dichloride or aluminum trichloride and a cyclopentadienyl-type monomer in chloromethyl methyl ether under polymerization conditions. Suitable alkylating polymerization conditions for preparing the polymeric ligand include a temperature in the range of from about xe2x88x9220xc2x0 C. to about 50xc2x0 C.
Another method for preparing the polymeric ligands involves anionic polymerization by reacting an alkali metal compound and a cyclopentadienyl-type monomer under polymerization conditions. Generally the reaction will be conducted in a diluent such as diethyl ether. Suitable conditions for anionic polymerization include a temperature in the range of from about 0xc2x0 C. to about 150xc2x0 C., preferably from about 0xc2x0 C. to about 100xc2x0 C., and more preferably from 0xc2x0 C. to 50xc2x0 C.
Alkali metal compounds suitable for preparing the polymeric ligand by anionic polymerization are represented by the formula ARxe2x80x2, wherein A is an alkali metal selected from the group consisting of lithium, sodium, and potassium and wherein Rxe2x80x2 is a hydrocarbyl group selected from the group consisting of alkyl, cycloalkyl, and aryl groups containing 1 to 12 carbon atoms. Preferably Rxe2x80x2 is an alkyl group containing 1 to 10 carbon atoms. Lithium alkyls containing 1 to 8 carbon atoms are especially preferred. Examples of preferred lithium alkyls include methyllithium, ethyllithium, propyllithium, butyllithium, pentyllithium and hexyllithium. Excellent results have been obtained with n-butyllithium and it is especially preferred. The alkali metal compound is generally present in an amount in the range of from about 0.1 mole to about 20 moles alkali metal compound per mole cyclopentadienyl-type monomer, preferably about 0.2 mole to about 10 moles, and more preferably about 0.5 moles to about 5 moles alkali metal compound per mole cyclopentadienyl-type monomer.
In one embodiment of the invention, a bridged polymeric ligand is provided. The bridged polymeric ligand is represented by the formula (Qxe2x80x2)n, wherein Qxe2x80x2 is a unit containing at least one bridged cyclopentadienyl-type group and wherein n is 1 to 5000, preferably 3-1000. The bridged cyclopentadienyl-type group is represented by the formula ZRZ, wherein each Z is individually a cyclopentadienyl-type group, and R is a bridging group and is an alkylene group containing from 1 to 12 carbon atoms, an aryl-containing group having from 6 to 12 carbon atoms, silicon-containing group, germanium-containing group, or tin-containing group. Preferably R is an alkylene group containing 1 to 10 carbon atoms.
Typical examples of bridged cyclopentadienyl-type monomers are 1-(9-(2-vinyl)fluorenyl)-2-(9-fluorenyl)ethane, (9-(2-vinyl)fluorenyl)(cyclopentadienyl)methane, (9-fluorenyl)(cyclopentadienyl)methane, 1-(9-(2-vinyl)fluorenyl)-2-(cyclopentadienyl)ethane, (9-(2-vinyl)fluorenyl)(1-indenyl)methane, 1-(9-(2-vinyl)fluorenyl)-1-(cyclopentadienyl)cyclopentane, (9-(2-vinyl)fluorenyl)(cyclopentadienyl)(1-cyclo-3-hexenyl)methane, (9-(2-vinyl)fluorenyl)(cyclopentadienyl)dimethylmethane, (9-fluorenyl)[1-(3-vinyl)phenylcyclopentadienyl]diphenylmethane, (9-(2,7-divinyl)fluorenyl)(1-(3-methyl)cyclopentadienyl)dimethylmethane, (9-(2-vinyl)fluorenyl)(cyclopentadienyl)silane, (9-(2-vinyl)fluorenyl)(cyclopentadienyl)dimethylsilane, (9-(2-vinyl)fluorenyl)(9-fluorenyl)diphenylsilane, (9-(2-vinyl)fluorenyl)(cyclopentadienyl)dimethylgermane, (9-(2-vinyl)fluorenyl)(fluorenyl)dimethylstannane, 1-(9-(2-vinyl)fluorenyl)-3-(cyclopentadienyl)propane, 1-(9-fluorenyl)-1-(methyl)-1-(1-(2-vinylcyclopentadienyl)ethane, (9-(2,7-diphenylfluorenyl)(1-(3-vinyl)cyclopentadienyl)diphenylmethane, bis(9-(l -methyl-4-vinyl)fluorenyl)diphenylmethane, bis(9-fluorenyl)dimethylmethane, (fluorenyl)(cyclopentadienyl)methyl)(1-(4-vinyl)phenyl)methane and mixtures thereof.
The method for preparing the bridged polymeric ligand comprises reacting at least one bridged cyclopentadienyl-type monomer and an initiator compound under polymerization conditions.
The bridged cyclopentadienyl-type monomers can be prepared by any method known in the art. Examples of such methods are disclosed in Stone et al. in J. Org. Chem., 49, 1849 (1984), European Published Application 524,624, and U.S. Pat. Nos. 5,191,132 and 5,347,026, the disclosures of which are incorporated herein by reference.
One method for preparing bridged cyclopentadienyl-type monomers involves reacting a cyclopentadienyl-type compound with an alkali metal compound, and then with a halogenated cyclopentadienyl-type compound. The halogenated cyclopentadienyl-type compound can be prepared by reacting a lithiated cyclopentadienyl-type compound and an organo halide, such as dibromoethane or dichloromethane.
Alkali metal compounds suitable for preparing the bridged cyclopentadienyl-type monomer include those defined above for preparing the polymeric ligand. Lithium alkyls containing 1 to 8 carbon atoms are preferred. Excellent results have been obtained with n-butyllithium and it is especially preferred. When preparing the bridged cyclopentadienyl-type monomer, the alkali metal compound is generally present in an amount in the range of from about 0.1 mole to about 20 moles alkali metal compound per mole cyclopentadienyl-type compound, preferably about 0.2 mole to about 10 moles, and more preferably about 0.5 moles to about 5 moles alkali metal compound per mole cyclopentadienyl-type compound.
Reaction conditions for reacting the cyclopentadienyl-type compound and the alkali metal compound to produce the bridged cyclopentadienyl-type monomer include a temperature in the range of from about 0xc2x0 C. to about 150xc2x0 C., preferably from about 0xc2x0 C. to about 100xc2x0 C., and more preferably from 0xc2x0 C. to 50xc2x0 C.
The at least one bridged cyclopentadienyl-type monomer is reacted with a suitable initiator compound under polymerization conditions to prepare the bridged polymeric ligand. Suitable initiator compounds include azobisisobutyronitrile, phenyl-azo-triphenylmethane, tert-butyl peroxide, cumyl peroxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, tert-butyl hydroperoxide, tert-butyl perbenzoate, boron trifluoride etherate, alkali metal compounds, zinc dichloride, and aluminum trichloride. Suitable alkali metal compounds include those described above for preparing the bridged cyclopentadienyl-type monomers.
Typically the reaction is conducted in diluents similar to those described above for radical, cationic, alkylating, and anionic polymerizations. As noted above, typical examples of such diluents include toluene, methylene chloride, chloromethyl methyl ether, and diethyl ether for the respective polymerization.
When preparing polymeric ligands containing at least one bridged cyclopentadienyl-type group, the initiator is generally present in an amount in the range of from about 0.0001 mole to about 20 moles initiator per mole cyclopentadienyl-type monomer, preferably about 0.001 mole to about 10 moles, and more preferably about 0.005 moles to about 5 moles initiator per mole cyclopentadienyl-type monomer.
Conditions for preparing the polymeric ligand containing at least one bridged cyclopentadienyl-type group vary broadly depending on the reactants employed. Generally the temperature is in the range of from about xe2x88x9280xc2x0 C. to about 150xc2x0 C. Suitable conditions are similar to those disclosed above for radical, cationic, alkylating, and anionic polymerizations.
The method is also suitable for the copolymerization of mixtures of bridged and unbridged cyclopentadienyl-type monomers. The term xe2x80x9cunbridgedxe2x80x9d as used herein refers to groups which are not connected by a bridging group. The mixtures can be selected so as to prepare catalyst systems capable of producing polymers having a broad molecular weight distribution and good environmental stress crack resistance. When polymerizing mixtures of bridged and unbridged cyclopentadienyl-type groups, typically the bridged cyclopentadienyl-type group will be present in an amount in the range of from about 0.001 mole to about 1000 moles per mole of unbridged cyclopentadienyl-type group, preferably from about 0.01 mole to about 100 moles per mole of unbridged cyclopentadienyl-type group.
The method is also suitable for the copolymerization of at least one bridged cyclopentadienyl-type monomer with styrene or other similar conjugated system. When employing a styrene comonomer, good results have been obtained when employing azobisisobutyronitrile as initiator and toluene as diluent.
The process for preparing polymeric metallocenes comprises reacting the polymeric ligand, an alkali metal compound, and a transition metal-containing compound.
The polymeric ligand contains a cyclopentadienyl-type group and can be prepared by any method described above.
The transition metal-containing compound is represented by the formula MX4, wherein M is a Group IVB or VB transition metal, preferably M is zirconium, hafnium, titanium, or vanadium, more preferably zirconium, hafnium, or titanium, and wherein each X is individually a hydrocarbyl group containing 1 to 20 carbon atoms, preferably 1 to 16 carbon atoms, an alkoxy group containing 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, an aryloxy group containing 6 to 20 carbon atoms, preferably 6 to 12 carbon atoms, a halide, preferably chloride, or hydride. Preferably X is a halide or a cyclopentadienyl-type group.
Alkali metal compounds suitable for preparing the polymeric metallocene include those defined above for preparing the polymeric ligand. Lithium alkyls containing 1 to 8 carbon atoms are preferred. Excellent results have been obtained with n-butyllithiun and it is especially preferred.
In preparing the polymeric metallocene, the alkali metal compound is generally present in an amount in the range of from about 0.1 mole to about 20 moles alkali metal compound per mole cyclopentadienyl-type group, preferably about 0.2 mole to about 10 moles, and more preferably about 0.2 moles to about 5 moles alkali metal compound per mole cyclopentadienyl-type group.
Suitable transition metal-containing compounds for preparing the polymeric metallocene include titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, vanadium tetrachloride, titanium tetrabromide, zirconium tetrabromide, hafnium tetrabromide, vanadium tetrabromide, titanium tetraiodide, zirconium tetrabromide, hafnium tetrabromide, vanadium tetrabromide, zirconium tetramethoxide, titanium tetramethoxide, hafnium tetramethoxide, vanadium tetramethoxide, zirconium tetraethoxide, titanium tetraethoxide, hafnium tetraethoxide, vanadium tetraethoxide, cyclopentadienylzirconium trichloride, cyclopentadienyltitanium trichloride, cyclopentadienylhafnium trichloride, cyclopentadienylvanadium trichloride, pentamethylcyclopentadienylzirconium trichloride, pentamethylcyclopentadienyltitanium trichloride, pentamethylcyclopentadienylhafnium trichloride, pentamethylcyclopentadienylvanadium trichloride, indenylzirconium trichloride, and indenyltitanium trichloride. Zirconium-containing and titanium-containing compounds are preferred and zirconium tetrachloride and cyclopentadienylzirconium trichloride are especially preferred.
In preparing the polymeric metallocene, the transition metal-containing compound is generally present in an amount in the range of from about 0.1 mole to about 20 moles transition metal-containing compound per mole cyclopentadienyl-type group, preferably about 0.2 mole to about 10 moles, and more preferably about 0.5 moles to about 5 moles per mole cyclopentadienyl-type group.
The polymeric ligand, the alkali metal compound, and the transition metal-containing compound are generally reacted at a temperature in the range of from about xe2x88x9280xc2x0 C. to about 150xc2x0 C., preferably from about xe2x88x9240xc2x0 C. to about 100xc2x0 C., and more preferably from 0xc2x0 C. to 50xc2x0 C.
Preferably the polymeric ligand and the alkali metal compound are contacted first, prior to contacting with the transition metal-containing compound. Typically the reactions will be conducted in a diluent such as tetrahydrofuran, pentane, or diethylether.
In another embodiment, polymeric metallocenes are represented by the formula [Qxe2x80x3MXm]n, wherein Qxe2x80x3 is a unit containing at least one fluorenyl-type group, M is a transition metal, each X is individually a hydrocarbyl group containing 1 to 20 carbon atoms, an alkoxy group containing 1 to 12 carbon atoms, an aryloxy group containing 6 to 20 carbon atoms, a halide, or hydride, m is 2 or 3, and wherein n is 1-5000, preferably 3-1000. Preferably X is a halide or a cyclopentadienyl-type group.
The polymeric metallocenes can be used in combination with a suitable cocatalyst to produce catalyst systems for the polymerization of olefins. Examples of suitable cocatalysts include any of those organometallic cocatalysts which have in the past been employed in conjunction with transition metal-containing olefin polymerization catalysts. Some typical examples include organometallic compounds ofmetals of Groups IA, IIA, and IIIB of the Periodic Table. Examples of such compounds include organometallic halide compounds, organometallic hydrides, and metal hydrides. Some specific examples include triethylaluminum, tri-isobutylaluminum, diethylaluminum chloride, diethylaluminum hydride, and the like. Other examples of known cocatalysts include the use of compounds capable of forming a stable non-coordinating counter anion, such as disclosed in U.S. Pat. No. 5,155,080, e.g. using triphenyl carbenium tetrakis(pentafluorophenyl)boronate or tris(pentaflurophenyl)boron. Another example would be the use of a mixture of trimethylaluminum and dimethylfluoroaluminum such as disclosed by Zambelli et, Macromolecules, 22, 2186 (1989).
Currently, organoaluminoxane cocatalysts are the preferred cocatalysts. Various techniques are known for making organoaluminoxanes. One technique involves the controlled addition of water to a trialkylaluminum. Another technique involves combining a trialkylaluminum and a hydrocarbon with a compound containing water of adsorption or a salt containing water of crystallization. Many suitable organoaluminoxanes are commercially available.
Typically the organoaluminoxanes comprise oligomeric, linear and/or cyclic hydrocarbyl aluminoxanes having repeating units of the formula 
wherein each Rxe2x80x3 is a hydrocarbyl group, preferably an alkyl group containing 1-8 carbon atoms, x is 2 to 50, preferably 4 to 40, and more preferably 10 to 40. Typically Rxe2x80x3 is predominantly methyl or ethyl. Preferably at least about 30 mole percent of the repeating groups have an R which is methyl, more preferably at least 50 mole percent, and still more preferably at least 70 mole percent. Generally in the preparation of an organoaluminoxane, a mixture of linear and cyclic compounds is obtained. Organoaluminoxanes are commercially available in the form of hydrocarbon solutions, generally aromatic hydrocarbon solutions.
An organoaluminoxy product can be prepared by reacting an organoaluminoxane and an oxygen-containing compound selected from the group consisting of organo boroxines, organic boranes, organic peroxides, alkylene oxides, and organic carbonates. Organo boroxines are preferred. One such method is disclosed in U.S. Pat. No. 5,354,721, the disclosure of which is incorporated herein by reference.
The amount of organoaluminoxane relative to the polymeric metallocene employed in the catalyst system can vary broadly depending upon the particular catalyst selected and the results desired. Typically, the organoaluminoxane is present in the amount of about 0.5 moles to about 10,000 moles aluminum per mole of metal in the polymeric metallocene, preferably about 10 moles to about 5,000 moles, and more preferably 50 moles to 5,000 moles.
The polymeric metallocene and the cocatalyst are generally contacted in the presence of a solvent or a diluent. Typical diluents include, for example, toluene, tetrahydrofuran, dichloromethane, heptane, hexane, benzene, and diethylether.
A variety of olefin compounds are suitable for use as monomers in the polymerization process of the present invention. Olefins which can be employed include linear, branched, and cyclic aliphatic olefins. While the invention would appear to be suitable for use with any aliphatic olefin known to be employed with metallocenes, those olefins having 2 to 18 carbon atoms are most often used. Ethylene and propylene are especially preferred. Often a second or third olefin (comonomer) having from 2 to 12 carbon atoms, preferably from 4 to 10 carbon atoms can be employed. Typical comonomers include propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 2-pentene, 1-hexene, 2-hexene, cyclohexene, 1-heptene, and dienes such as butadiene. Of these, 1-hexene is preferred.
The polymerization processes according to the present invention can be performed either batchwise or continuously. The olefin, polymeric metallocene, and organoaluminoxane cocatalyst can be contacted in any order. It is preferred that the polymeric metallocene and the organoaluminoxane are contacted prior to contacting with the olefin. It may be advantageous to dry the reaction product before contacting with the olefin. Generally a diluent such as isobutane is added to the reactor. The reactor is heated to the desired reaction temperature and olefin, such as ethylene or propylene, is then admitted and maintained at a partial pressure within a range of from about 0.5 MPa to about 5.0 MPa (70-725 psi) for best results. At the end of the designated reaction period, the polymerization reaction is terminated and the unreacted olefin and diluent vented. The reactor can be opened and the polymer can be collected as a free-flowing white solid and dried to obtain the product.
The reaction conditions for contacting the olefin and the catalyst system can vary broadly depending on the olefin employed, and are those sufficient to polymerize the olefins. Generally the temperature is in the range of about 20xc2x0 C. to about 300xc2x0 C., preferably in the range of 50xc2x0 C. to 110xc2x0 C. The pressure is generally in the range of from about 0.5 MPa to about 5.0 MPa (70-725 psi).
The present invention is particularly useful in a gas phase particle form or slurry type polymerization. A particularly preferred type particle form polymerization involves a continuous loop reactor which is continuously charged with suitable quantities of diluent, catalyst system, and polymerizable compounds in any desirable order. Typically the polymerization will include a higher alpha-olefin comonomer and optionally hydrogen. Generally the particle form polymerization is conducted at a temperature in the range of about 50xc2x0 C. to about 110xc2x0 C., although higher and lower temperatures can be used. The reaction product can be continuously withdrawn and the polymer recovered as appropriate, generally by flashing the diluent and unreacted monomers and drying the resulting polymer.
The olefin polymers made with the present invention are useful in preparing articles prepared by conventional polyolefin processing techniques, such as injection molding, rotational molding, extrusion of film, pipe extrusion, and blow molding.